Rock drill



W. A. SMITH.

Rock DRILL.

APPLICATION FILED AUGJS. 1920.

W. A. SMITH.

ROCK DRILL.

APPLICATION FILED AUGJB |920.

Patented Apr. 25, 1922. I

2 SHEETS-SHEET 2.

,d ATToR Y A VMT-ED Mares) o;Fificr; l

' WILLIAM'A; SMITH; 0E PHILLIPSBURGQNEW JERsEY',"AssIGi\ToR To INGERsoLL-IRAND a citizen of the United States, and a residentv two different positions.

f ooMPAivmoE JERSEY CITY, 'NEW JERSEY,v CORPORATION or NEW JERsEY."

- Rock :DRiLIiv/ Application sied August i3,f192o. seiiai 110.403,351. ,t

of Phil-lipsburg,jcounty of .'Warren, State of NewJersey, have invented certain new and useful Improvements vin Rock Drills, of which the following is a specification.

. Thisl invention relates to fluid pressure op- Verated drills. of the hammer type, but more particularly to a rock drill of such type hav ing a dierential piston provided with a main head and forwardlyV andrearwardly extendingqshanks or extensions, with a constant-pressure chamber exerting constant pressureupon the vrear end of the rearwardly-extending'shank. f

In adrill of this class/[the fluid pressure l is Ydistributed -to the front and reanen'ds of :thej main cylinder herein frontofand behind the main lpistonlcead in any :suitable manner, and in the present instancey this distribution fis.v controlled partly by the; rear- ;wardly 4 extending piston shank .and partlyV by :an automaticlvalve so-thatffthe machine may-,be termed asemi-valveless trock .drill The^ primary object oftheinventionisto;

produce late admissionof the actuating fluid or live; air pressure against the'rear surface of; the main lhea'dron the rearward stroke, in order to afford as long back 'travel for the piston as possible, and produce a late cut-off on the forward stroke. By producing as long' admissionof air as possible againstv the rear pressure surface of the mainI piston head, I am enabled to take advantage of the -fulL power of the-piston hammen,v

. The-inventionfis illustratedin the accom- .panying, drawings whichshow two preferred forms of tliemachine.

, Figures l and 2 are diagrammatic longi- Y tudinal sectional-elevations of a rockdrill embodying the invention, showing the piston .hammerin two different positions, and

` Figures 3 and t are similar views of a modification showing the piston hammer in Referring tothe drawings, A represents thecylinder of a rock drill having the chuck through which the drill steel C, is inserted in the usual'manner in position to receive vthe impact blows of the reciprocating piston hammer, which comprises the main piston head D having the Jforwardly 'extending reduced shank E and the rearwardly extending Shsmk the reduced neck A l' with;` the shank..

,Q ,forming the shoulder portion FY of. full diameter.- j

Specification of Iettersifatent. .*Ptoeitl'ted 71922. ,Y

`The main piston head D reciprocates in t'he larger bore Jofthe cylinder andthe cylinderis provided with a back cylinder portion or. backhead -I havinga bore Lofl ,maller diameterto receive the piston shank lare provided Awith a suitable arrangement admitted at the` inletfport P and controlled The cylinder A and the back head K Vferentportions ofi-the cylinderfor actuating Vthe piston.,y

,7 Actuating*fluid'asair Vunder pressure is '17071:

Iby the usual throttle valvefQfv,The chamber sure is constantly .exertedon the pressure surface Sjef therearwardly extending piston therear of the back 'head K is under c I [constant pressure l as shown so-that .pres-v shank. The, actuating fluidpassesfrom their L l constant pressure Cllall'lber through: the

' T-,jgandfthe :passage Ufin thebackhead Kf registering with the 1 passage "V. .in Qthe Icylinder'Le; tout: throughv the'fport' tol the forward,:endof the -main cylinder bore J in t cylinder iisprovided with .theexhaust .port X. 1The. passages U andV also vform anexfliaustpassage on thexjforwardl stroke ofthe .piston because the passage U communicates by means of theannular groove Y with the ,portZ'opening from the passage a leading to the rear Vpressure surface. b of thevalve O.

Thispres'sure surface b. isobviously subject the valve.

end .ofthe main cylinder bore J behind the Thesupplyfof fluid pressure to therear f mainpiston head D isfcontrolled partlyby i the shoulder H of the piston shank F andi partly by the `valve O, .andfthe manner'in which this controlis Veffected forms one of the principal features vof this invention. v As -showna forward admission portl cjopensf` Yinto they smaller bore L of the cylinder cas- I' Award passage c. .Another rearward admis,-

sion` port f communicates with the valve.

chamber Z byV means of the rearward pasling and communicatesv with the valve cham?, ,ber aofthevalve O vby means of'the'for- -v nsage g and also.communicates',with` the con- A port j in the back head K between theV main cylinder bore J and the forward end of the valve :chambery Z subjects the vforplied to the rear of the main cylinder head ward pressure surface 7c of the valve OV to a fluctuating pressure in the operation ofthe machine.

ThevalveO Y Y but is V(':onveniently provided with aY front head oV and a rear head p `connected by'the reduced neck q and the function of this valve Vis to control communication vbetween the-forward"admission passage e' andthe rearward admission V'passage g in order to produce a late'admission of fluid pressure against the rear pressure surface` of the main head D on the rearward stroke and prolong the admission. o has a long backtravel, longer than custom- 'Ihe piston thus ary in rock drills of this type and has a later cut-olfl on the forwar'd stroke.

' In the operation of the'machine, let it be assumed that'the piston is at' the forward end of its stroke and is about to start on the back stroke as indicated in Figure l.

The cylinder `is shown exhausting throughy the exhaust port Xand pressure is also ex'- haustedf from :the front fof the valve O2 through the port j. The live pressure on the rear surface o of the valve O has caused the valve to vthrow over or move to its forward i position as indicated invligure l, closing .cause the lforward* admission communication betweeny the' forward and.

lrearward admission passages; e and g. Y' i y 'Thev pistonis lready for.L the rearward stroke bytheadmission of fluid under pres sureltofthefront end of the cylinder through the, passages U and V from the constant pressure chamber R. As the piston travels back, the exhaust port X to the backof the main head D is closed and the admission port T to the forward end ofthe cylinder and the port Z to vthe rear end Z2 of the valvey Y O areclosech'but the shoulder H at the neck of the piston over-runs the forward admission port c, without admitting pressure to the rearfsurface'of Vthe main head Dbe passage e is stillclosed by the Vvalve O; Y

After the main head D over-runs the Cylu inder' exhaust port-X, the exhaust from the forward end of the cylinder is opened,

Y which also opens the rear endV b of the valve 0 to exhaust through the passage a.,

vport Z, annular` groove Y and passages 'U the valve O, which throws the valve to its rear position indicated in Figure 2, thus .opening communication between the forward may be'of any suitable .formv and rearward admission passagese and` g,

.and supplying full pressure behind the main headjD to drive the piston forward. Y

Owing to the fact that no pressureis sup- D ywhen the forward admission port yc is unf` covered by the piston shoulder H, the piston has. a substantially long rearward stroke, before the forward and rearward admission passages e and g ,are placed in communica- 75 tion bv the action of the valve O, and on the other hand, the piston is given a late cut-olf on the forward stroke, because cut-off does not take place when the rearward admission port j is over-runebytheYpiston'shoulderH, 80 Vbut is delayed until the vforward admission u port c is over-run by the piston as indicated o' in Figure l. y I

The construction shown in Figures 3 and` 4 is substantially the same as lshown iii-Figures l and 2 except that an additionalanticompression orreliever port 1' is kprovided. and the forward end ofthe cylinder communicates by means of thepassage s with the valve chamber d', to relieve compression `after the piston closes the main exhaustfport X. The valve O is provided with anladdi-y tional auxiliary head t, the rear surface b of which is subjectedto a'fluctuating pressure through the passage 0a', andthe auxiliary head t controls an atmospheric' port-'u oomu municating with the valve chamber andv the' reliever port passage s." Theanti--compression-or reliever port r is over-run and' closed bythe piston before the admission of fluid 100 pressure to the front ven'dofthemain'-cylinn -der bore J. When' they valvefOis thrown to its forward position as shown in Figure, communication is cut off between the reliever Vport 1" andthe atmosphere by meansof the 1051 head t. i

I claim: f f 1. In a'uid operated rock drill of the hammer type, the combination of a -cylinder and a differential piston subject to constant pressure on one ofits forwardly acting pres-A sure surfaces, means controlled bythe piston for supplying motive fluid to the rearwardly acting pressuresurface ofthe piston, a forward admission port and an admissionjport rearward of said forward' admission port for supplying motive fluid to the other forwardly acting pressure surface of the piston and a fluid actuated valve for controlling communication between forward and rear- 1.270

ward admission passages leading to said forward and rearward admission ports. Y

2. In a fluid operated rock drill ofthe hammer type, the combinationof a cylinder and a differential piston subject toconstant pressure on one of its forwardly acting pres: sure surfaces, means controlled by the piston for supplying motive fluid to the rearwardly l acting pressure surface of the piston, aforward admission port and an admission port VV l' Y rearward of said V forward admission port forl supplying motive fluid to 'the other forwardy hammer type, the combination of'a cylinderV and piston, means controlled by the piston for supplying motive fluid to the forward end of the cylinder, and an exhaust port and an anti-compression port for the cylinder, a forward admission port and another admission port rearward of said forward admission port for supplying motive fluid to the rearward end of the cylinder, and a fluid actuated valve for controlling communication between forward and rearward vadmission passages leading to said forward and rearward admission ports and for controlling communication' between said Aanti-compression port and the atmosphere.

4. In a fluid operated rock Vdrill of the hammer type, the combination of a cylinder and a piston, means controlled the piston A' for supplying motive fluidy to thev forward end of the cylinder, andy an exhaust port and an anti-compression port forthe cylindena forward admission port-and another admis- Y sion port rearward of said forward admission port for supplying motive fluid to the rearward end of the cylinder, and a iiuid actuated valve subject to fluctuating Vpressure on opposed operative surfaces forcontrolling communication between forward and,

rearward admission passages leading to said forward` and rearward admission portl and for controlling communication between saidanti-compression port and theatmosphere.

In testimony whereof I have signed this specification.

WILLIAM A.. SMITH.l f; 

